1. Field of the Invention
The invention is directed to an intermittently operated needle thread snubber for controlling the size of a needle thread loop presented to the loop taker of a lockstitch sewing machine.
2. Description of the Prior Art
It is known to provide a needle thread snubber between a needle and needle thread take-up in a lockstitch sewing machine for limiting the size of the needle thread loop presented to the loop taker. However, commonly used thread snubbers have their drawbacks in that they snub the needle thread not only during loop presentation but also at other stages of stitch formation including stitch setting, and with a thread snubber effective at stitch setting, the needle thread tensioning device must be set at a high value which increases the likelihood of thread breakage. It is therefor desirable to provide for the automatic control of a thread snubber in such fashion that the snubber is caused to apply a drag on needle thread during loop presentation and to remove the drag during stitch setting.